Expansile Member

ABSTRACT

An expansile member is described. The expansile member may be used on a delivery device or may be used for occlusive purposes within the vasculature.

RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application Ser.No. 61/919,651 filed Dec. 20, 2013 entitled Expansile Member, which ishereby incorporated herein by reference in its entirety.

BACKGROUND OF THE INVENTION

Liquid embolic, which can be thought of as biocompatible glue, is oftenused in intravascular interventional procedures to embolize a sitewithin the vasculature. Delivery of the liquid embolic can be difficultsince the delivery device (i.e. catheter) may stick to the liquidembolic during delivery of said embolic. Additionally, potentialbackflow of the liquid embolic during delivery may cause embolic tomigrate away from the treatment site. Reflux of the liquid embolic maycause the delivery device to stick to the embolic mass. An expansilemember mounted to the delivery device would prevent these issues.

An expansile member could also be used as a treatment device to aid invarious scenarios (i.e. aneurysms, atrial septal defects, patent foramenovale, left atrial appendage occlusion, patent ductus arteriosis,fistula, arterio-venous malformations, occlusion in the peripheralvasculature) where space filling is required.

SUMMARY OF THE INVENTION

An expansile member is described.

In one embodiment an expansile member is connected to a retention memberand mounted to a delivery device.

In another embodiment an expansile member is connected to a retentionsleeve and mounted to a delivery device.

In another embodiment a catheter includes an expansile member connectedto a retention member.

In another embodiment a catheter includes an expansile member connectedto a retention sleeve.

In another embodiment an occlusive expansile member is described.

In another embodiment an occlusive expansile member for treating holesin the heart is described.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an elevation of an embodiment of an expansile member of theinvention mounted to a delivery device;

FIG. 2 is an elevation of an embodiment of an expansile member of theinvention mounted to a delivery device;

FIG. 3 is an elevation of an embodiment of an expansile member of theinvention mounted to a delivery device;

FIG. 4 is an elevation of an embodiment of a retention sleeve and anexpansile member of the invention;

FIG. 5 is an elevation of an embodiment of a retention sleeve and anexpansile member of the invention;

FIG. 6 is a perspective view of an embodiment of a retention sleeve andan expansile member of the invention;

FIG. 7 is a perspective view of an embodiment of a retention sleeve andan expansile member of the invention;

FIG. 8 is an elevation of an embodiment of an expansile member of theinvention mounted to a delivery device;

FIG. 9 is an elevation of an embodiment of an expansile member of theinvention mounted to a delivery device;

FIG. 10 is an elevation of an embodiment of an occlusive device of theinvention; and,

FIG. 11 is a depiction of an embodiment of an occlusive device of theinvention delivered to a target location by an embodiment of a deliverydevice of the invention.

DESCRIPTION OF EMBODIMENTS

FIGS. 1-3 illustrate a delivery device 10 with an expansile member 14and retention member 12 mounted on the delivery device 10. The deliverydevice 10 can be a catheter, hypotube, or other device used to delivermatter within the vasculature. In one example delivery device 10 is amicrocatheter that may be used to deliver liquid embolic to a sitewithin the vasculature.

The expansile member 14 is comprised of a hydrogel—an expansile,hydrophilic polymer. Hydrogels are often incorporated in embolizationcoils, where their expansile properties aid in space filling forapplications such as aneurysm embolization. Hydrogels typically expandwhen exposed to material, such as blood. This response is based on thepH of the material to which the hydrogel is exposed. Thus, hydrogelsutilized for intravascular procedures are designed to expand on contactwith a substance having a pH within a pH range typical of blood.

Typically practitioners who regularly use liquid embolic materialsencounter several problems. One problem is wash-out, which occurs when ahigh blood flow rate results in the liquid embolic getting washed away,especially in the opposite direction of the intended treatment site. Onemethod of mitigating this problem is building up a dam of liquid embolicaround the tip of the microcatheter. The inclusion of the expansilemember 14 will eliminate the need for this dam since the expansilemember 14 will fill the space between the microcatheter 10 and thevessel wall, thus preventing wash-out of the embolic and in effectacting as a dam.

Another problem is reflux of the embolic. As the clinician attempts tofill the treatment area (located distal of the distal tip of thedelivery device), embolic may start to reflux proximally toward thedistal tip of the catheter, especially as there is less resistance inthis direction. Reflux may cause the catheter to get stuck to theembolic mass, in effect getting ‘glued’ into place. The expansile member14 prevents reflux by filling the space around the distal tip of thedelivery device thus blocking backflow.

FIGS. 1-3 show the expansile member 14 assuming a variety of shapes.Though only three are shown in these figures, namely ovular,frustoconical and cylindrical, respectively, it is to be understood thatthe expansile member 14 may assume a great variety of other shapes,including but not limited to circular, rectangular, non-symmetrical,polygonal, cubical, etc. Thus, the shapes shown are just examples of thevarious shapes said expansile member can assume. Each of the members 14has a proximal end or portion 13 and a distal end or portion 15. Theembodiments incorporating an unconstrained shape having increasingdiameters, such as the frustocone of FIG. 2, are oriented such that thedistal end 15 has a greater diameter than the proximal end 13.

Regardless of the unconstrained shape of the expansile member, it isdesirable for the distal portion 13 of member 14 to expand to fill orsubstantially fill the gap between the delivery device and the wall ofthe vessel through which the delivery device is delivered. In the casewhere the microcatheter is used to deliver liquid embolic, the embolicis preferably delivered from the distal end of the microcatheter. Thehydrogel may be configured to expand to its full diameter within 15-25minutes, which should be sufficient time to advance the microcatheter tothe target site based upon current clinical practices.

In a typical embolic procedure, a guide catheter is used to navigate afirst portion of the vasculature. A guidewire is then used to navigatethe remaining portion to the particular target location within thevasculature, and, finally, a microcatheter is delivered over thisguidewire. The guidewire is subsequently withdrawn. Once themicrocatheter is in place, liquid (or other) embolic is deliveredthrough the microcatheter to treat the target site. Thus, the totalmicrocatheter diameter (which includes the unexpanded expansile membermounted to a portion of the microcatheter) must be smaller than theinner diameter of the guide catheter in order to navigate through saidguide catheter.

A retaining member is used to secure the expansile member 14 to thedelivery device 10. In one example the retaining member is a coil 12placed over the expansile member 14. Various coil properties can affectthe expansile member 14. For example, a tightly wound coil or one withminimal gap length between windings will limit the amount of hydrogelthat expands through the coil upon exposure to blood. A loosely woundcoil or one with significant gap length between windings will allow morehydrogel expansion through said windings.

Various sizes can be used for all the elements (delivery device 10,expansile member 14, coil 12). One example configuration is as follows:the delivery device 10 is a microcatheter which has a 0.013″ innerdiameter and 0.021″ outer diameter. The de-hydrated (pre-expanded)expansile member 14 has an inner diameter of 0.021″ and a maximum outerdiameter of 0.029′ and is 0.09″ long. The retaining member is a straighthelical over-coil 12 with an inner diameter of 0.036″, made from a0.001″ filar, and is 0.130″ long. Note the expansile member 14 sits overthe microcatheter 10, thus the inner diameter of the expansile member 14matches the outer diameter of the microcatheter 10. The coil 12 ispositioned over the expansile member 14 and both ends are pinched downonto the microcatheter body 10 with a coining tool, or via handcrimping. The pinched ends of the over-coil 12 may be secured to themicrocatheter 10 via UV adhesive. The expansile member 14 may be securedto the microcatheter 10 with a UV adhesive and further restrained by theover-coil 12. In one example the over-coil 12 may be tensioned such thatit sits into the unexpanded expansile member 14. In another example theover-coil 12 sits over or at the periphery of the unexpanded expansilemember 14. The microcatheter 10 may be provided sterile with theincorporated ring and over-coil, and may include a hydrophilic coatingto reduce friction when navigating the vasculature. In one example theexpansile member 14 is not coated with a hydrophilic coating, saidcoating could delay expansion of the expansile member 14.

FIGS. 4-9 illustrate another embodiment. In this embodiment instead of acoil 12, the retaining member is a retention sleeve 16, which physicallysits over expansile member 14. The retention sleeve 16 is affixed to themicrocatheter body 10 and acts like a cage for the expansile member 14(not shown in FIGS. 4-9), which sits underneath the retention sleeve 16.The retention sleeve 16 includes one or more cells 18. These cells 18can be thought of as open spaces in the sleeve 16. These cells 18 may belaser cut from sleeve 16. When expansile member 14 expands on contactwith blood, it will expand through these cells 18. The cells 18 may takeon any number of shapes including the ones shown in the Figures. Shapesas simple as slits, or complex geometric patterns can be used. In oneexample shown in FIGS. 4-5, the sleeve 16 is initially a plate withcells 18 inscribed from the plate. The plate can then be rolled into thesleeve shape shown in FIGS. 6-7. In another example the sleeve in FIGS.6-7 is already formed and cells 18 are inscribed from the sleeve. Thesleeve 16 can be made from an elastomeric material. The material shouldbe sufficiently strong to pull the fully expanded hydrogel through aguide catheter, in the case where the guide catheter has a smallerdiameter than the gels' fully expanded diameter. The over sizing of theexpanded gel, in one example, can be as high as 50% greater than theguide catheter inner diameter. The material should also be compliantenough such that the caged gel is able to freely expand to the desireddiameter. In one example Polyblend is used. In a more specific examplePolyblend 1100 is used. In one example the cells 18 are configured suchthat the resulting shape of the expansile hydrogel member 14 has a shapesimilar to that of a football. The smaller diameter end regions of thefootball shape help lead the expanded gel back into the guide catheterduring withdrawal of the device 10 while protecting the hydrogel frombeing sheared by the guide catheter orifice.

Retention sleeve 16 can be secured to the delivery device 10 (i.e.microcatheter) shaft by adhesive bonding, thermal fusion, or viamechanical means (i.e. retaining rings and/or marker bands).

FIG. 10 illustrates another embodiment where an expansile member (notshown) is used in an occlusive device 20, where said device 20 is usedfor such purposes as occluding holes in a heart, more specifically holesin a baby's heart. The expansile member is used in a device 20, whichhas an undulating profile. An external sleeve 16, which has anundulating profile sits over an expansile member which sits underneaththe sleeve. The sleeve 16 contains a number of cells 18. This sleeve 16is similar to the retention sleeve 16 of FIGS. 8-9, just with arelatively more complex geometric shape than shown in those Figures. Theexpansile member, once exposed for a sufficient time to blood, willexpand out of the cells 18. The narrow middle portion of occlusivedevice 20 sits physically at the hole in the heart while the widerportions immediately next to the middle portion would sit on either sideof the hole to prevent blood from migrating through the hole. Theexpansion of the hydrogel expansile member will allow enhanced spacefilling around the hole, better preventing any blood seepage through thehole. In one example the sleeve functions as a hollow shell housing anexpansile material (i.e. hydrogel), which fills the area within theshell. In another example the occlusive device contains an innerpolymeric or metallic core, the expansile material sits around thisinner core, and the shell sits around the expansile material. In thisparticular example, the amount of filler expansile material can becustomized based on the thickness of this inner core. In another exampleutilizing either scenario just described, the expansile material (i.e.hydrogel), rather than filling the entire space underneath the shell,sits only immediately under the surface of the shell. Bonding means suchas adhesive can be used to secure the expansile material to the innersurface of the shell.

The occlusive device 20 is delivered via a delivery device 10 (i.e.microcatheter) and can be connected to a pusher 21 with a detachmentzone 22 which can be degraded or severed to detach the occlusive device20 from pusher 21. Depending on the properties of sleeve 16 (i.e.restraining strength or thickness), the sleeve 16 may initially bulgeout a bit when the expansile member starts to expand upon contact withblood, before the expansile member protrudes from cells 18. This bulgingshould not affect the overall shape of the occlusive device, as theocclusive device should have an undulating profile so the middle of thedevice bridges the hole while the proximal and distal bulged ends of thedevice 20 fill the space on either side of the hole.

FIG. 11 illustrates another embodiment where an expansile member is usedin an occlusive device 30, where said device is used for such purposesas aneurysm occlusion, left atrial appendage occlusion, vessel shutdown, fistulas, or other vascular malformations where embolization isrequired. In FIG. 11 the occlusive device 30 is shown to occlude ananeurysm 24, where said aneurysm is a bulge in blood vessel 26. Theocclusive device 30 is comprised of an external sleeve 16 that sits overan expansile member (not shown). This sleeve 16 is similar to theretention sleeve 16 of FIGS. 8-9, just with a relatively more complexgeometric shape than shown in those Figures. The expansile member, onceexposed for a sufficient time to blood, will expand out of cells 18.This will help to more thoroughly fill the malformation. In one examplethe sleeve 16 functions as a hollow shell housing an expansile material(i.e. hydrogel) which fills the area within the shell. In anotherexample the occlusive device contains an inner polymeric or metalliccore, the expansile material sits around this inner core, and the shellsits around the expansile material. In this particular example, theamount of filler expansile material can be customized based on thethickness of this inner core. In another example utilizing eitherscenario just described, the expansile material (i.e. hydrogel), ratherthan filling the entire space underneath the shell, sits onlyimmediately under the surface of the shell. Bonding means such asadhesive can be used to secure the expansile material to the innersurface of the shell.

Depending on the properties of sleeve 16 (i.e. restraining strength orthickness), the sleeve may initially bulge out a bit when the expansilemember starts to expand upon contact with blood, before the expansilemember protrudes from cells 18. Device 30 is delivered via a pusher 21and is delivered through a delivery device 10 (i.e. microcatheter). Thepusher may contain a severable detachment zone linkage to sever thepusher from occlusive device 30.

The embodiments described in FIGS. 10-11 utilize a pusher with aseverable and/or degradable detachment zone to deliver the occlusivedevice to the treatment site within the vasculature. Thermal,electrolytic, or mechanical means may be utilized to degrade thisdetachment zone, thus detaching the occlusive device from the pusher.

Although the invention has been described in terms of particularembodiments and applications, one of ordinary skill in the art, in lightof this teaching, can generate additional embodiments and modificationswithout departing from the spirit of or exceeding the scope of theclaimed invention. Accordingly, it is to be understood that the drawingsand descriptions herein are proffered by way of example to facilitatecomprehension of the invention and should not be construed to limit thescope thereof.

What is claimed is:
 1. A medical device for delivering liquid embolic toa target site comprising: a delivery device; an expansile memberdisposed around a distal end of the delivery device; a retaining membersecuring the expansile member to the distal end of the delivery device.2. The medical device of claim 1 wherein the delivery device comprises acatheter.
 3. The medical device of claim 1 wherein the delivery devicecomprises a microcatheter.
 4. The medical device of claim 1 wherein thedelivery device comprises a hypotube.
 5. The medical device of claim 1wherein the expansile member comprises a shape selected from the groupovular, frustoconical, cylindrical, rectangular, non-symmetrical,polygonal, and cubical.
 6. The medical device of claim 1 wherein theexpansile member comprises a hydrogel.
 7. The medical device of claim 1wherein the expansile member has a proximal portion and a distal portionand wherein the distal portion has a diameter greater than a diameter ofthe proximal portion.
 8. The medical device of claim 1 wherein theretaining member securing the expansile member to the distal end of thedelivery device comprises a coil.
 9. The medical device of claim 1wherein the retaining member has a diameter less than an expandeddiameter of the expansile member.
 10. The medical device of claim 1wherein the retaining member comprises a retention sleeve attached tothe delivery device and at least partially containing the expansilemember.
 11. The medical device of claim 10 wherein the retention sleevecomprises cells through which the expansile member expands in anexpanded state.
 12. A method of preventing proximal flow of a liquidbeing delivered into a vessel in a distal direction comprising: placinga distal end of a delivery device at a desired location in a vessel;sealing a circumferential gap between the distal end of the deliverydevice and a wall of the vessel; injecting a liquid into the vesselthrough a lumen of the delivery device in a distal direction.
 13. Themethod of claim 12 wherein sealing a circumferential gap between thedistal end of the delivery device and a wall of the vessel comprisesallowing an expansile member to expand around the distal end of thedelivery device until the circumferential gap is filled.
 14. The methodof claim 13 wherein allowing an expansile member to expand comprisesallowing a hydrogel to expand.
 15. A system for occluding blood flowcomprising: an expansile member; a retaining member surrounding theexpansile member and containing openings through which the expansilemember expands when assuming an expanded state.
 16. The system of claim15 wherein the retaining member comprises a sleeve having an undulatingprofile.
 17. The system of claim 15 further comprising a pusher catheterhaving a distal end releasably attached to a proximal end of theexpansile member with a detachment zone.
 18. The system of claim 17further comprising a delivery catheter containing the pusher catheter,expansile member and retaining member.
 19. The system of claim 15wherein the expansile member and retaining member comprise a septaldefect occluder.
 20. The system of claim 15 wherein the expansile memberand retaining member comprise an aneurysm occluder.